The present invention relates in general to printed circuit xe2x80x9cbreadboardxe2x80x9d assemblies using surface mount type components and more particularly to the use of a universal mounting structure or circuit pattern that will allow for the placement of a variety or range of different types, styles, and sizes of surface mountable components and which also allows for multiple component placement location options on the same structure.
In the electronic circuit design field it is common practice to build a test or prototype circuit using components that are xe2x80x9cbreadboardedxe2x80x9d or interconnected in a circuit configuration determined by the circuit designer whereby the circuit function can be observed, tested, and evaluated.
On occasion when circuits will be prototyped or breadboarded using components that have leads, wires, pins, or other means of interconnection intended for mounting in holes, a common practice would be to use one of the many breadboards or prototyping boards available for this purpose. When the circuit designer wishes to use components intended for surface mounting when prototyping a given circuit design they usually must develop a custom circuit board pad and conductor pattern dedicated to a particular requirement because surface mount components do not have lead structures that can be fashioned in a way that will allow them to be interconnected or mounted to a typical breadboard intended for leaded components. When circuit designers do develop, dedicated custom mounting pad and circuit pattern for their application they usually use industry standard mounting pads or xe2x80x9cfootprintsxe2x80x9d for the individual devices used.
Circuit designers have long needed a breadboarding medium for use with surface mount components that will allow for the use of many different component types, styles, and sizes, and that will also allow for many different component mounting location and interconnection configurations. Such a medium would preferably allow the circuit designer to select from a range of components xe2x80x9cfootprintsxe2x80x9d to work with, and allow the use of components with two or more terminals or connection points. The present invention fulfills this need.
The universal interconnection structure for microelectronic devices of Rotast U.S. Pat. No. 3,716,761, and the universal leadless chip carrier mounting pad of Daberkoe U.S. Pat. No. 4,489,365 address only the mounting of various surface mount integrated circuits but do not provide for the mounting of discrete surface mount components such as resistors, capacitors, diodes, transistors and other surface mount devices. The above mentioned references are not really within the same scope as the present invention in that they can be utilized for the mounting or breadbording of an entirely different family of devices comprised of many types of surface mount devices other than integrated circuits and with the principle utility being different in nature than the above mentioned invention.
The electronic component mounting wafers for repeated connection in a variety of circuit designs by Christiansen U.S. Pat. No. 3,833,838 does provide a useful means of connecting components with leads but does not address the needs of surface mount applications in that the designs and patterns are not intended for surface mount devices and have little utility for their application, and with the main goal of the above invention being heat isolation and reusable mounting wafers for use with leaded components.
Whatever the precise merits, features, and advantages of the above cited references, none of them achieves or fulfills the purpose of the present invention, the universal component mounting structure for surface mountable electronic devices.
It is the purpose of the present invention to provide circuit designers with the means to develop and test circuits using surface mount electronic devices without the need to design and produce custom patterns for dedicated circuit boards, and to facilitate the testing of individual components or groups of components in an efficient fashion. The present invention fulfills the above mentioned purpose by providing conductive circuit patterns of lands that provide multiple areas on the same structure for mounting several components of differing sizes, with the above mentioned circuit patterns or lands being arranged with conductor and insulator patterns that provide multiple component mounting footprints that do not conform to industry standard footprint specifications, but are universal in nature.
Furthermore the present invention can be utilized to produce many different surface mount based circuit designs in production quantities if so desired as the potential benefits of the present invention are not necessarily limited to prototyping or breadboarding exclusively.
The universal component mounting structure for surface mountable electronic devices described herein when used alone in the form of an individual circuit board or circuit wafer provides a convenient means for circuit designers to breadboard with surface mount devices. The present invention can also be utilized on the same circuit board with custom or dedicated circuit patterns to provide for a breadboarding, prototyping, or circuit modification area in adjunct to the dedicated circuit patterns. The present invention can also be utilized on the same circuit board with industry standard mounting footprints for integrated circuits and other devices using both surface mount and leaded technologies in order to provide a surface mount breadboarding area in adjunct to those components.
The present invention is comprised of electrically conductive circuit patterns or lands spaced by or applied to an insulating material or substrate. The dimensions of the circuit patterns or lands and the insulating gaps or spaces between the lands are designed so that the required mounting footprints for a range of surface mount device sizes will be available for mounting of a given component, with the size and location of the component being determined by the circuit designer. The present invention does not require a fixed method to determine the dimensions of the lands and spaces for each design since it is the goal of the present invention to provide a range of differing patterns, each being suitable for a given family of component types or size ranges on a common structure. The only requirement is that the minimum and maximum widths or lengths of the desired range of mounting footprints to provided for. A typical footprint for a two terminal surface mount device would be comprised of two conductive attachment points spaced by an insulating area. For example, a few industry standard sizes for surface mount resistors and capacitors are commonly know as 805,1206, and 1210, the sizes being 0.080xc3x970.050 in., and 0.120xc3x970.060 in., and 0.120xc3x970.100 in. respectively. The terminations or connection points on these examples are on the ends of the longer axis. For a universal mounting pattern to accommodate placement of any one of these example devices, an insulating gap of 0.070 in. or less between the two conductive lands and the combined widths of the lands and the insulating gap are at least 0.130 in. or more is required. Multiple variations of circuit land and gap patterns base on the above mentioned concept can then be combined on a common printed circuit structure to provide a prototyping breadboard if so desired. Three terminal devices can also be accommodated by designing land patterns comprised of two or more parallel and one or more perpendicular conductive circuit lands with the insulating gaps between the lands.
In both the above descriptions of mounting structures for two or three terminal devices it is important to consider that wide ranges of devices can be provided for by changing the dimensions of the circuit land and gap design according to the size of footprint range desired. The concept of the present invention is also applicable to devices having more than three terminal, but the practicality of the invention may become limited above four or six terminals or connection points on a driven device.
The foregoing and other objects, features and advantages of the invention will be apparent from the following more particular description of the preferred embodiments of the invention, as illustrated in the accompanying drawings.